This can sometimes be done by installing a double layer of 5/8" sheetrock over the area to a point that is at least 18" away from the flue or by installing a sheet metal plate between the flue and the combustible surface.

It's vital you leverage from experienced investors to mitigate your own headaches/financial loss. 

This became vital to this acquisition, as there were multiple offers that we ultimately beat out as a result. 

Putting down roots is vital. 

typically shingles will run you $20/bundle (3 per 100 sq ft or 1 Square) for lower end, install depends much on tear off and prep or shingle over and prep, we have opted for Steel when ever reasonable to do so, it costs about 10-20% more up front, but will out last me, and does not have Ice damming problems we see with regular shingles in the north. standard shingles, you can expect about 1/2-2/3 the stated warranty actual life span, so 40 year shingles will last about 20 years, but steel, even 40 year has been known to far exceed the 40 year warranty, I can typically get a roof done in steel with a 2 layer tear off, and steel installed for around $4-6K for a 13 Sq roof thats material, labor and disposal, I just has a 11 sq one does with dimensional shingles (steel wasnt practical) for $2,700 including tear off and disposal. keep in mind, the cheap guy may not be the best value, there are a lot of hacks out there, and anyone with a pitch fork, a hammer and a nail gun calls them self a roofer. 

Risk can be mitigated somewhat,  but not personally investigating adds another layer of difficulty to the deal. 

The majority of the vitals were done in the past 10 years, so the seller endured most of the major capital improvements.

From my understanding, this creates several "layers" of legal protection. 

This means that proactively doing things to retain tenants is vital.

The property is in decent shape structurally, I will be putting another layer of shingles over the roof (one layer currently about to end of life span), Exterior needs a fresh coat of paint also.